1. Field of the Invention
The present invention relates generally to a telephony system, and more specifically to a virtual private branch exchange (PBX) system for a packet-switching network (PSN).
2. Discussion of the Background
A PBX is an automatic telephone switching system that enables users within an organization to place calls to each other without having to access a public switched telephone network (PSTN). Users can also place calls to outside numbers via the PBX. PBXs are typically located on the premises of a customer and provide a great deal of control and flexibility in the customer""s communications. PBXs are well known and are described, for example in Stallings, xe2x80x9cData and Computer Communications,xe2x80x9d 4th Edition, MacMillan Publishing Co., New York, 1994, which is incorporated herein by reference.
One approach to implementing a PBX involves a virtual PBX call processing method in which a packet switching system establishes a virtual circuit between each distinct pair of user packet stations in a group. The user packet stations exchange signaling packets via the virtual circuits and respond to such packets by coordinating the initiation and disconnection of voice, data, or image calls. All call processing, including the provision of features, such as call forwarding and automatic call back, is accomplished by the stations without the aid of the switching system. Thus, all of the intelligence of the system is on the terminal side of the system and not on the network side. Consequently, telephony agents and terminals are required to process inbound and outbound calls and perform routing. No dynamic tracking of locations is performed by this system, and all of the terminal locations are static.
Methods of using Internet based communication standards for telephone communication have been developed for use with conventional PBXs. These methods simply (1) permit remote telephone access to an existing PBX system via a PSTN and (2) link Internet Protocol (IP) telephony clients to an existing PBX system via an H.323 gateway. H.323 is an ITU (International Telecommunications Union) standard that provides a set of specifications for equipment and services for use with multimedia communications over a network. An example of how IP telephony clients are linked to an existing PBX system via an H.323 gateway is described in http://quicknet.net/support/AppNotes/AN00004.htm, which is incorporated herein by reference. However, such systems still incorporate a conventional PBX, which handles call referencing and switching.
Accordingly, one object of this invention is to provide a virtual PBX system for a packet-switching network (PSN), where the intelligence of the virtual PBX system is located in the network rather than in the terminals.
It is another object of the present invention to provide a PBX system for a PSN that does not require telephony equipment.
It is yet another object of the present invention to track locations of users of the virtual PBX system in real time so that users are not required to maintain static locations.
It is still yet another object of the present invention to track users""locations for call and message delivery each time a user connects to the PSN.
It is still a further object of the present invention to provide connectivity between the virtual PBX system of the present invention and existing public switched telephone networks (PSTNs) and existing PBX systems.
These and other objects are achieved according to the present invention by providing a novel method, system, computer program product, and data structure in which login information is received from a data device. The login information includes an alias identifying a user at the data device and a network address identifying the location of the data device on the PSN. The user""s PBX extension is associated with the network address of the data device, and calls are routed to the user""s PBX extension to the data device on the basis of the network address of the data device. In this manner, a virtual PBX system for a PSN is implemented. Advantageously, the intelligence of the virtual PBX system is located in the network instead of in the terminals (e.g., the data device).
Preferably, information that uniquely identifies a user is linked to the user""s PBX extension. As a result, the virtual PBX system of the present invention does not require conventional telephony equipment to route calls.
The location of the user can be dynamically tracked by storing the network address of the data device when the user logs onto the PSN with the data device. If the user logs onto and off of the PSN with different data devices, then the inventive virtual PBX system is able to track the location of the user by dynamically storing the network address of the data device that is currently connected to the PSN under the user""s alias. When the user disconnects from or logs off of the PSN, the virtual PBX system disassociates the network address of the data device that is being disconnected from the PBX extension of the user. Preferably, the network address of the data device is an Internet Protocol (IP) address.
Additionally, known gateways provide connectivity between the virtual PBX system of the present invention and existing PSTNs and existing PBX systems. Thus, the virtual PBX system can complement, or be used independently of, conventional telephony networks.